Combustion engine with revoluting pistons forming a closed kinematic chain



June 11, 1968 1.. NIEMAN D COMBUSTION ENGINE WITH REVOLUTING PISTQNS FORMING A CLOSED KINEMATIC CHAIN Filed June 8, 1966 5 Sheets-Sheet 2 4770NEH5 June 11, 1968 NIEMAN COMB S ION ENGINE W D ITH REVOLUTING PISTONS RMING A CLOSED KINEMATIC CHAIN Filed June 8, 1966 5 Sneets-Sheet I5 Leon NlE-MAND nlasoujewm #(fi nnwa A rraeA/s Vs 5 Sheets-Sheet 4 x/vwswrae giro/z m Q w m mu June 1 1. 1968 MEMAND COMBUSTION ENGINE WITH REVOLUTING PISTONS FORMING A CLOSED KINEMATIC CHAIN Filed June 8, 1966 LEON NIEMAND BV wamfiwmm June 11. 1968 L. NIEMAND 3,387,596

TION ENGINE WITH REVOLUTING PISTONS ORMING A CLOSED KINEMATIC CHAIN COMBUS 5- Shets-Sheet 5 Filed June 8. 1966 lA/VEWTQZ LEON. NIEMAND 5V WMMEQM td umme.

United States Patent F 3,387,596 CQMBUSTTON ENGZNE WETH REVOLUTING PISTONS FORMING A CLOSED KINEMATIC CHAIN Leon Niemand, Warsaw, Poland, assignor to Politechnika Warszawska, Warsaw, Poland Filed dune 8, 1966, Ser. No. 556,028 Claims priority, application Poland, June 9, 1965, P 109.449 2 Claims. (Cl. 123-8) ABSTRACT 0? THE DISCLQSURE An improved rotary-piston internal combustion engine in which five rotary pistons form a closed kinematic chain and circulate within a static, oval cylinder. The movement of the pistons is controlled by means of two lateral rotors, which also consist of five segments articulated to one another by means of bolts. On the bolts, which function as the common axis of the segment articulations and of the articulations of said pistons, there are afiixed the rollers which roll over the races equidistant to the outline of the cylinder. The two rotors take over all the forces originating from the gas pressure and from the inertia of the pistons. The engine is provided with fiywheel and the lubrieating and the cooling systems.

This invention has for its object to provide an improved rotary-piston internal combustion engine in which the rotary pistons form a closed kinematic chain.

There are already known rotary-piston internal combustion engines in which the rotary-piston is mounted on an eccentric transmitting the torque on the engine shaft through an internally toothed transmission gear which simultaneously constitutes the kinematic bond determining the movement of the piston.

Essential disadvantage of such a constructional solution are the great difficulties connected with the supply of the cooling medium to the rotary piston requiring to be cooled due to the cumulation of thermal streams from each combusion process, and owing to the necessity of securing suitable working conditions to the bearings and gear transmission.

There are also known constructional solutions of rotarypiston engines in which the pistons are swingably mounted on the engine shaft and rotate within an oval cylinder without forming a closed kinematic chain.

An essential drawback of this kind of engine is the balancing of forces acting upon the piston, by the lateral surface of the cylinder, and therefore the notable friction and the detrition of elements cooperating with one another.

Another disadvantage of these engines is the penetration of the fuel into the engine through the interruptions between the pistons which causes perturbations in the operation of the engine and creates the danger of explosions.

There are also known such constructional solutions in which four pistons articulated with one another essentially secure the tightness of the working spaces, but the power collection method used in these solutions causes that the rotary system has in fact two degrees of freedom in consequence of which the action of the gas pressure exercised on the pistons and their forces of inertia are transmitted upon the piston race through the medium of radial sealings. A characteristic feature of the said constructional solutions is the fact that the race of the cylinder constitutes a kinematic bond for the articulations of the pistons and thus it forces their circulation.

Known is also the constructional solution according to which the movement of the four-bar linkage is controlled by means of two cams mounted on the shaft. But also in Fatented June 11, 1968 this case the rotor has two degrees of freedom, and the cams do not univocally determine the movement of the four-bar linkage, and consequently the duty is taken over through the medium of radial sealings by the lateral surface of the cylinder which surface becomes then the kinematic bond forcing the movement of the pistons.

To the above described group of engines appertains the engine according to British Patent 1,030,200. In this engine the piston movement is determined by the lateral surface of the cylinder, hence all the forces resulting from the unbalance of the pistons and sealing rolls and also the resultant gaseous forces are transmitted by the inner surface of the cylinder which fact is the true reason of the want of durability of this kind of engine.

The authors of the arrangement according to British Patent No. 235,095 have, indeed, applied to control of the sealing vanes through rolls which are rolling in closed cam races, however the task of such a control is not to discharge the lateral surface of the cylinder, but it is a necessity resulting from the adopted constructional solution.

Aim of the present invention is to remove the above mentioned disadvantages of rotary-piston engines i.e. to construct such an engine in which by causing a forced movement of the pistons, the lateral surface of the cylinder is exposed to the pressure of gases only, without taking over the forces of inertia of the pistons.

In connection with the above, it has been found serviceable to use at least five pistons forming a closed kinematic chain, the forces of inertia of which pistons are taken over through the medium of the lateral segments of the rotors, by two races controlling the movement of the pistons. Such a task is constructionally unrealizable if a four-bar linkage is used.

The subject of the invention is shown, by way of example, in the accompanying drawing, in which FIG. 1 is a five-piston system,

FIG. 2 is one of the rotors which controls the movement of the pistons and transmits the torque on the shaft,

FIG. 3 is a diagram of the engine with pistons being in a position in which the volume of the working chamber is the smallest,

FIG. 4 is a diagram of the engine with modified inlet openings, the pistons being in a position in which the volume of the working chamber is the greatest.

FIG. 5 is a concrete example of execution of the engine according to the invention.

FIG. 6 is a schematic view of the engine, the lateral cover being removed from the side of the rotor transmitting the torque on the transmission shaft.

The engine according to the invention is composed of a few principal parts: a cylinder, a system of five pistons forming a closed kinematic chain, two lateral rotors.

The outline 1 of the cylinder forms a curve equidistant to the curve over which are moved the vertexes of the articulated polygon 2. in case of an articulated equilateral pentagon, such a theoretical curve is formed by one of the group of Lamme curves determined according to the formula:

in which 12 is the function of the angle (,0 of rotation of the radius-vector of the articulated pentagon vertex.

It has been found that this curve may be replaced with great accuracy by a convenient ellipse with an axis ratio a/b contained within a range of 1.3-2. In the concrete case, for the given side of the pentagon an ellipse for which a/b=l.625 has been chosen.

The chosen ellipse differs from the above mentioned theoretical one by some microns which of the technical point of view is of no importance but admits a considerable technological simplification. The outline of the cylinder may also constitute the locus of end points of equal sections of the bisectrix of the angle contained between two adjacent sides of the articulated pentagon, measured from the above described ellipse on the outside.

Within the cylinder there are circulating five pistons 3 forming a closed kinematic chain but kinematieally not bonded with one another i.e. there is no force interaction between the pistons.

The pistons form a closed chain in such a manner that on the end of one piston is articulated to the beginning of the next piston by means of an expanding sealing sleeve. Within every piston here is a recess 4, shaped as shown in the drawing, which recesses form, together with the lateral surface of the cylinder, working chambers.

The closure of the kinematic chain has been obtained by using expanding sealing rollers 5 which are placed between the vertex protrusions of two adjacent pistons. Sealing of the working chambers has been obtained by means of radial sealing strips 6 placed in expanding sealing rollers 5, and by m ans of lateral scaling strips 7 placed on both sides of each piston.

The sealing strips 6 are always positioned along the angle contained between two adjacent sides of the articulated pentagon 2, thus assuring the most favorable sealing conditions. In consequence of the chosen outline 1 of the cylinder, the radial sealing strips 6 when circulating together with the pistons, do not perform radial movements.

In order to control the movement of the pistons, there have been applied two auxiliary rotors consisting of five segments 8 articulated to one another by means of bolts 9 in such a manner that these bolts and the expanding sealing rollers 6 have a common axis. On the bolts 9 there are affixed the rollers 10 which when rolling over the race 1 control the movement of the segments, and through the pivots 12 also the movement of the pistons. On said pivots fixed in holes 13 of the rotor segments, there are mounted through the holes 14 the pistons 3 in such a manner that every two rotor segments together with the piston placed between them, form one rigid system. In consequence of this fact, the forces originating from the inertia of the pistons and from the gas pressure, are not transferred from one piston to the other, nor to the lateral surface of the cylinder, but are transmitted on the race 11 by means of rollers 10.

Owing to such an arrangement, the elements transmitting the forces and exposed to high duty operate on the outside of the cylinder and are placed beyond the zone of high temperatures. Simple strength computations admit to ascertain that admissible pressures between the roller 10 and the race 11 are not exceeded. One of the rotor segments is provided with a bow 15 on the inner surface of which there is the race 16 over which is reciprocating the roller, or the outer ring of the bearing 17 fixed on the crank-pin 18 of the crank of the flywheel 19. Thus, by means of this segment, the torque resulting from the action of gaseous forces on the individual pistons, is transmitted from the articulated rotor on the shaft 20.

The cylinder of the engine is closed on both sides by the lateral walls 21 and 22, which are screwed together with the cylinder by means of screws 23. The lateral walls have an inner profile 24 shaped in such a manor, that the outer cylindrical protrusions 25 of the pistons 3 during their movement are contained within said profile.

In cylinder body there are inlet holes intended for filling the working chambers with mixture, and outlet holes for removing the combustion gases, two variations as to their quantity and spacing being foreseen.

In the first version, shown in FIG. 3, there are two inlet openings 26 and 27, the opening 27 alone being conneeted to the carburetor, while the opening 26 is connected directly to the atmosphere, and there are also two outlet openings 28 and 29 discharging to a common outlet pipe not shown in the drawing. Said openings are located asymmetrically in relation to the shorter axis of the cylinder profile, the openings 29 and 26 being situated nearer to said axis than the openings 27 and 28.

In the second variation, shown in FIG. 4, there are three openings: two outlet openings 28 and 29 and one inlet opening 30. In both variations, a sparking plug 31 is placed within the cylinder body, namely the mouth of the opening 32 connecting the working chamber of the piston to the zone of the electrodes of the sparking plug, is recessed in relation to the shorter axis of the cylinder profile in a direction opposite to the rotation sense of the engine shaft, as much as to obtain optimal ignition timing, securing the best conditions for the thermodynamic process.

The cylinder, the rings 33 and lateral covers 34 and 35 are joined together into one whole by means of screws 36 and form a closed space. The engine shaft 20 is mounted in two bearings 37 and 38 fitted in the Walls of the lateral covers 34 and 35. At the side of bearing 37, the end of the shaft extends outwardly the engine, while the other end of theshaft is provided with a blind excavation 39.

The cover 40 is shaped in such a manner that it supports the bearing 38, the cylindrical part 41 of cover 40 being stuck in the excavation of the shaft. On both sides of the shaft, flywheels '19 and 42 are mounted.

The engine operates according to the four-stroke scheme of the thermodynamic cycle. In the position as shown in FIG. 3, the piston 3 is in such a position that it closes, together with the lateral surface of the cylinder, a smallest volume of the working chamber. In this space the mixture combustion process takes place at practically constant volume. In the same time, in the working chamber of the piston 3' the mixture compression process is performed, while in the working chamber of the piston 3" the expansion of the combustion gases takes place.

In the course of circulation of the pistons in the cylinder, in each working chamber the following work cycle of the engine is achieved: combustion of the fuel mixture, expansion of combustion gases, exhaust of combustion gases initially through the outlet opening 28 and subsequently also through the outlet opening 29, scavenging with clean air at simultaneously opened inlet opening 26 and outlet opening 2? and utilizing the injective elfect of the combustion-gas stream, filling with clean air and fuel mixture at opened both inlet openings, filling with fuel mixture through the inlet opening 27, compression.

During a single revolution of the engine shaft, the above described working cycle is performed by all the five pistons. Thus, during a single revolution of the engine shaft, five ignitions take place, in the chamber of each piston a four-stroke working cycle being performed, and the scavenging of the Working chamber being made by means of clear air when the volume of said Working chamber is the smallest.

The variation of the invention as shown in FIG. 4, Comprises also such an arrangement of the outlet and inlet openings that the scavenging process of the working chambers is achieved by means of fresh fuel mixture, as it is the case in carburetor two-stroke piston engines.

In both both variations, the ignition occurs at the very moment at which the corresponding working chamber attains the smallest volume. At the same time the radial sealing strip approaches the opening 32, in the slot between the piston and the lateral surface of the cylinder, positioned between the opening 32 and the radial sealing strip 6, governing a pressure practically equal to the final compression pressure, because in consequence of unfavorable space conditions existing in this slot, the propagation of the flame is rendered very difiicul-t.

In the adjacent working chamber, at this time the compression process is on the point of being achieved, in consequence of which on both sides of the radial sealing strip 6 the pressure is practically equal. Thus, when said strip passes away the opening 32, there does not occur the scavenge of combustion gases from the chamber in which the combustion actually takes place, into the chamber in which the fuel mixture has been compressed.

The cooling of the outer parts of the engine is performed by a generally used water mantle, While the cooling of the pistons is done by a tightly closed system. The Cooling fluid supplied through the opening 43 flows through the openings 45 in the shaft and 46 in the flywheel hub 19, through the channel 47 and is then supplied to the inside 49 of the piston by means of a flexible conduit 43. From there it flows through the flexible conduit 50 to the excavation 39 of the shaft and subsequently the cooling fluid returns through the opening 51 of the cover 40 to the cooler. In this manner a closed circulation of the cooling fluid is obtained enabling the coolant to be pressed through the piston without any danger of arising a coctail effect.

What I claim is:

1. A rotary-piston internal combustion engine in which the rotary pistons form a closed kinematic chain comprising an articulated polygon, said pistons circulating in a stationary cylinder the outline of which constitutes a curve equidistant in relation to the curve of motion of the vertexes of the articulated polygon, or of the loci of end points of equal sections of the bisectrix of the angle contained between adjacent sides of this polygon, measured on the outside of the curve, for the equilateral pentagon the said curve being one of the group of Lamme curves determined according to the formula in which p is the function of the angle (p of rotation of the radius-vector of the pentagon vertex, or one of the ellipses for which the axis ratio ta/b is contained within a range of 1,32, the said piston forming together with the corresponding rotor segments separated rigid systems which are provided with rolls mounted in the axis of the articulations of rotors existing on both sides of the cylinder, the said rolls resting on races the outline of which being equidistant in relation to the curve over which the vertexes of the polygon are moving, every two adjacent pistons being separated from one another by means of an expanding sealing roller, the axis of said rolls being simultaneously the axis of the corresponding expanding sealing roller.

2. A rotary-piston internal combustion engine according to claim 1, in the cylinder body of which there is an inlet opening intended for scavenging and filling the working chambers with clean air.

References Cited UNITED STATES PATENTS 3,036,560 5/1962 Geiger 12317 RALPH D. BLAKESLEE, Primary Examiner. 

